Menopausal Estrogen and Estrogen-Progestin Replacement Therapy and Breast Cancer Risk

TLDR

Unresolved questions remain about whether.

Abstract

COLLABORATIVE REanalysis of more than 90% of the world's epidemiological data on the relationship between menopausal hormone replacement therapy (HRT) and breast cancer risk, it was found that longer durations of recent, but not past, use of HRT increased breast cancer risk, particularly among leaner women and for tumors that were less clinically advanced. 1Unresolved issues include the extent to which the findings were due to a biological effect of hormones rather than issues of screening and ascertainment.The data were also insufficient to determine whether a combined estrogen-progestin regimen increased risk beyond that associated with estrogen alone.In 1994, we published data on HRT and breast cancer risk from a follow-up study conducted among former participants in a breast cancer screening program. 2 Cases were diagnosed through 1989.Those data were included in the collaborative analysis. 1In this article, we expand our previous analysis to include cases diagnosed in the follow-up study through 1995, almost doubling the total number of cases.The collection of additional data on mammographic screening and use of the combined estrogen-progestin regimen allowed us to address some issues left unresolved. METHODS Follow-up StudyStudy subjects were participants in the Breast Cancer Detection Demonstration Project (BCDDP) conducted between 1973 and 1980.We previously described a follow-up study begun in 1979 involving a subset of BCDDP participants. 2In brief, the follow-up study included (1) all screening participants who underwent breast surgery during the screening period, with no evidence of malignant disease (n = 25 114);(2) all subjects who had recommenda-tions by the project for a surgical consultation but did not have either a biopsy or aspiration performed (n = 9628); and (3) a sample of women who had neither surgery nor recommendation for